CVE-2002-0558 in FTP Server
Summary
by MITRE
Directory traversal vulnerability in TYPSoft FTP server 0.97.1 and earlier allows a remote authenticated user (possibly anonymous) to list arbitrary directories via a .. in a LIST (ls) command ending in wildcard *.* characters.
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Analysis
by VulDB Data Team • 05/19/2019
The vulnerability identified as CVE-2002-0558 represents a directory traversal flaw within the TYPSoft FTP server version 0.97.1 and earlier implementations. This security weakness specifically affects the LIST command functionality when processing directory listings with wildcard patterns, creating a significant exposure that could allow unauthorized access to system directories beyond the intended scope. The vulnerability operates through a carefully constructed sequence where an authenticated user can manipulate the LIST command to traverse directory structures and access files or directories that should remain restricted.
The technical mechanism underlying this vulnerability stems from inadequate input validation and path resolution within the FTP server's command processing logic. When a user issues a LIST command with a pattern ending in wildcard characters such as ., the server fails to properly sanitize or validate the directory traversal components within the command. This allows an attacker to inject directory traversal sequences using the .. notation, which when combined with wildcard patterns, can bypass normal directory access controls and enumerate files in parent directories. The vulnerability specifically targets the LIST command processing rather than other FTP commands, making it a targeted issue within the server's file listing functionality.
The operational impact of this directory traversal vulnerability extends beyond simple information disclosure to potentially enable more severe attacks. An authenticated user can leverage this flaw to map the entire file system structure, discover sensitive files, and potentially identify other vulnerabilities within the system. The ability to list arbitrary directories provides attackers with valuable reconnaissance information that could facilitate further exploitation attempts. Additionally, the vulnerability may affect system integrity by allowing access to configuration files, log files, and other system resources that could contain sensitive information or provide pathways for privilege escalation.
This vulnerability maps to CWE-22 - Improper Limiting of a Pathname to a Restricted Directory, which categorizes weaknesses related to insufficient path validation in applications. The flaw aligns with ATT&CK technique T1083 - File and Directory Discovery, as it enables adversaries to enumerate system directories and file structures. The vulnerability also demonstrates characteristics of improper input validation, which is commonly addressed through proper sanitization of user-supplied input and implementation of strict path resolution controls. The attack vector requires authentication, making it a user-accessible vulnerability that could be exploited by insiders or compromised accounts.
Mitigation strategies for this vulnerability should focus on implementing proper input validation and path sanitization within the FTP server's command processing logic. System administrators should immediately upgrade to TYPSoft FTP server versions that have patched this vulnerability, as the original affected versions are no longer supported. Implementing strict input filtering for directory traversal sequences and ensuring proper path resolution during LIST command processing will prevent exploitation. Additionally, network segmentation and access controls should be implemented to limit the impact of potential exploitation, while monitoring systems should be deployed to detect unusual LIST command patterns that might indicate attempted exploitation. The vulnerability highlights the importance of validating all user-supplied input and implementing robust access controls to prevent unauthorized directory traversal operations.